1. Field of the Invention
The present invention generally relates to toilet tanks and, more particularly, is concerned with a toilet tank water flow shutoff apparatus for preventing leakage and overflow of toilet water.
2. Description of the Prior Art
Most toilets have a system of levers and valves in conjunction with a water holding tank to control water flow in and out of the toilet bowl proper. These systems are primarily necessary to prevent leakage and overflow of water after a flush. Most toilet tanks have a float that is movable with the water level in the tank during flush cycles. The float operates a water inlet valve that opens to refill the toilet tank upon lowering of the water from a predetermined level and closes once the tank has refilled to the predetermined level.
Actuation, usually by depression, of a flush lever causes unseating of a drain plug in the bottom of the tank during a flush cycle, causing the water in the tank to be released through a bottom discharge opening. The float descends in response to lowering of the water level from the predetermined level and operates to open the water inlet valve to initiate refilling of the tank with concurrent re-seating of the drain plug. As the toilet tank is refilled with water, the float ascends in response to the rise of the water level and when the water level returns to the predetermined level operates to close the water inlet valve to prevent any further supply of water to the toilet tank.
A problem exists where the water in the tank drops from the predetermined level due to a leak rather than a flush such as when the drain plug does not seat properly upon refilling of the tank. The leakage may be sporadic, continual or catastrophic. In any case, the float will operate the water inlet valve to remain open with water flowing into the tank to replace the water lost by the leak. If a backup or plugging situation should arise as a result of normal use of the toilet or external factors affecting the sewer system connected to the toilet, the presence of such leakage condition would likely result in overflow of water from the toilet bowl.
Various devices have been developed to address the problem of toilet overflows. Representative examples of such devices are disclosed in U.S. Pat. No. 4,402,093 to Luker et al., U.S. Pat. Nos. 4,498,203 and 4,538,307 to Barnum et al. and U.S. Pat. No. 5,062,166 to Krenecki. These devices, however, and do not address the problem of leaks.
Other devices address the problems of both toilet overflows and leaks. Representative examples of such devices are disclosed in U.S. Pat. No. 4,843,657 to Orr and U.S. Pat. No. 5,232,011 to Royalty. The Orr and Royalty devices operate only once the water level in the toilet tank reaches a predetermined level. Thus, if a leak occurs before the water reaches this particular level upon refilling after a flush, these devices would not shut off the water inlet valve in the toilet tank until such time as this predetermined level is reached.
Consequently, a need still exists for a toilet tank water leakage and overflow prevention system that will overcome the problems of the prior art without introducing new ones in their place.